Braking roller



United States Patent O 3,511,350 BRAKING ROLLER Hans vom Stein, Wermelskirchen, Germany, assignor to Hans vom Stein, o.H.G., Dhunn, Rhineland, Ger- US. Cl. 193-35 21 Claims ABSTRACT OF THE DISCLOSURE A braking roller for use in roller conveyor systems comprises a shaft which is fixedly mounted in the frame of the conveyor system, a liquid-filled housing having a cylindrical shell and two end walls which are rotatable on the shaft so that the shell can rotate in response to frictional engagement with an article which is caused to travel along the rollers of the conveyor system, a piston installed in the housing against rotation with reference to the shaft and dividing the interior of the housing into a pair of chambers which can communicate by way of one or more passages in the piston, cams provided on the piston and on the end walls of the housing to cause reciprocatory axial movements of the piston in response to rotation of the shell, and one or more automatic regulating valves provided in the passage or passages of the piston to offer to the flow of liquid a resistance which increases proportionally with rotational speed of the housmg.

BACKGROUND OF THE INVENTION The present invention relates to roller conveyors in general, and more particularly to improvements in braking rollers which are utilized in such conveyors to regulate the speed of goods.

It is already known to install in a roller conveyor one or more braking rollers which serve to regulate the speed of goods. Such braking rollers are installed at one or more points of the roller conveyor and may but need not be equidistant from each other. Their purpose is to insure that the speed of conveyed goods remains below a predetermined limit, for example, in order to prevent the goods from piling up on the roller conveyor and to thus insure that each article reaches the end of the conveyor ahead of and spaced from the next-following article. Another purpose of braking rollers is to prevent the articles from being propelled with excessive force against stops which are normally provided at the discharge end of a roller conveyor. For example, a crate or a box could be deformed, damaged or destroyed in response to excessive impact against a fixed stop or against the preceding crate or box at the discharge end of the roller conveyor. The braking rollers are usually installed in such a way that their peripheral surfaces extend into the path of and can be frictionally engaged by the undersides of conveyed articles.

Certain types of presently known braking rollers for use in roller conveyors are provided with braking devices which are operated in automatic response to rotation of the cylindrical shell of a braking roller, such rotation being caused by the article which travels along the conveyor and engages the external surface of the shell. The braking device comprises a housing which is fixedly secured to the shaft of the braking roller. The shaft is fixedly mounted in the frame of the roller conveyor and the housing is installed in the interior of the rotary shell. This housing is formed with two axially parallel bores each of which accommodates a reciprocable piston and each piston has an end portion which extends from the respective bore and constitutes a follower tracking a cam provided on the adjoining end wall of the shell. When the shell rotates, its cams cause the pistons to move in opposite directions and to pump a braking fluid which fills two chambers in the interior of the shell. The two chambers are in communication by way of a channel through which the braking fluid flows in response to axial displacement of the pistons. An adjustable screw serves as a means for throttling the flow of braking fluid through the channel.

A drawback of the just described braking roller is that its braking action can be regulated by a screw which is accessible only in response to complete dismantling of the braking roller. Moreover, the braking action of the roller is not dependent on the speed at which the shell rotates but solely on the position of the aforementioned screw. Therefore, such braking rollers are unsatisfactory for use in roller conveyors which are intended for transport of goods at different speeds or whereon the speed of goods changes during transport. Such conventional braking rollers produce an excessive braking action upon a slowly moving article and an insufiicient braking action upon an article which is conveyed at a high speed. The construction of such rollers is complicated and the adjustment of braking action consumes too much time so that the conveyor is idle for extended periods of time whenever it is to be converted from transport of slowly moving goods to transport of rapidly advancing goods, or vice versa.

SUMMARY OF THE INVENTION One of the objects of my present invention is to provide a braking roller whose braking action varies automatically in response to changes in speed of conveyed articles.

Another object of the invention is to provide a braking roller whose braking action can change during engagement with an article.

A further object of the invention is to provide a simple, relatively inexpensive and rugged braking roller which can be readily installed in presently known roller conveyors without necessitating substantial alterations in the design of such apparatus.

An additional object of the invention is to provide a braking roller which can be used in roller conveyors for transport of bulky, compact, heavy, lightweight, short and/or long goods and which need not be adjusted when the conveyor is converted from transport of one type of goods to transport of another type of goods.

A concomitant object of the invention is to provide a novel rotary housing for a braking roller of the above outlined character.

An ancillary object of the invention is to provide a ibraking roller which consists of a small number of relatively simple parts, whose parts can be mass-produced in known machinery, and which requires a minimum of maintenance.

Still another object of the invention is to provide a braking roller which can discriminate between heavy and lightweight goods as well as between rapidly moving and slowly advancing goods, and which automatically produces a braking force which is proportional to the bulk, speed and/ or kinetic energy of the goods.

A further object of the invention is to provide a braking roller which can be used to regulate the speed of smooth-surfaced or rough-surfaced goods.

The improved braking roller is utilized in roller conveyors or the like and comprises a shaft, means provided in the roller conveyor for holding the shaft against rotation, a hollow housing including a cylindrical shell and two end walls rotatably mounted on the shaft so that the housing can rotate in response to engagement between the external surface of the shell and an article which is caused to travel along the roller conveyor, a liquidfilled compartment defined by the housing and the shaft, a piston axially movably mounted on the shaft and dividing the compartment into a pair of chambers, cooperating cams provided on the housing and on the piston to move the latter back and forth in response to rotation of the housing so that the speed of axial movement of the piston is a function of rotational speed of the housing, at least one passage provided in the piston and extending between the two chambers of the compartment, and regulating valve means provided in the passage to throttle the flow of liquid between the chambers at a rate which increases in response to increasing rotational speed of the housing whereby the piston tends to decelerate the housing with a force which is a function of the rotational speed of the housing, i.e., a function of the speed at which an article which engages the external surface of the shell travels along the roller conveyor.

The piston may be provided with one or more passages and the valve means may comprise a separate valve for each passage or groups of valves for groups of passages.

The cams are preferably face cams which are provided on the end walls of the housing and on the axial ends of the piston and operate in such a way that one cam of the piston engages the cam of the adjoining end wall when the piston moves in one direction whereby the other cam of the piston is moved along the cam on the other end wall, and vice versa. The lead of all of the cams is preferably the same, and the cams of the two end walls are preferably angularly offset by 1-80 degrees with reference to each other.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved braking roller itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial sectional view of a braking roller which embodies one form of the invention, the section being taken in the direction of arrows as seen from the line II of FIG. 2;

FIG. 2 is a transverse vertical sectional view as seen in the direction of arrows from the line IIII of FIG. 1;

FIG. 3 is an enlarged elevational view of a regulating valve in the braking roller of FIGS. 1 and 2;

FIG. 4 is a partly elevational and partly axial sectional view of a second braking roller, the section being taken in the direction of arrows as seen from the line IV-IV of FIG. 5; and

FIG. 5 is a transverse vertical sectional view as seen in the direction of arrows from the line VV of FIG. 4.

DESCRIPTION OF THE .PREFERRED EMBODIMENTS The braking roller of FIGS. 1 to 3 comprises a shaft having externally threaded end portions 12 by means of which the shaft can be fixedly installed in a frame 75 of a roller conveyor. The frame 75 constitutes a means for holding the shaft 10 against rotation. The median portion of the shaft 10 is surrounded by a sleeve 11 of synthetic plastic material which is fixedly secured thereto and is provided with two axially parallel external ribs or splines 38 located diametrically opposite each other (see FIG. 2). The braking roller further comprises a housing including a cylindrical shell 18 whose ends are aflixed to two end walls or caps 16 of the housing by radially extending screws 20 or analogous fasteners. If desired, the caps 16 can be soldered, glued, welded or otherwise permanently secured to the end portions of the shell 18. The caps 16 are coaxial with the shaft 10 and each thereof ac- 4 commodates an antifriction bearing 24 whose inner race 28 is aflixed to the shaft 10 and whose outer race 26 is mounted in the respective cap. The peripheral surface of each cap 16 is formed with a circumferential groove for a sealing ring 22 and each cap is further provided with an internal recess for an annular sealing element 32 which surrounds the adjoining portion of the shaft 10. The caps 16 define with the shell 18 and with the sleeve 11 of the shaft 10 an annular compartment 19 which is sealed by the elements 22 and 32. Disk-shaped nuts 30 mate with the end portions 12 of the shaft 10 and overlie the outersides of the respective bearings 24.

The inner axial ends of the caps 16 are provided with helical face cams 34, 36 which are angularly offset by 180degrees. The lead of the cam 34 is the same as that of the cam 36. The compartment 19 accommodates an annular pumping member or piston 39 which is reciprocable along the sleeve 11 and comprises an outer cylindrical portion 40 which is adjacent to the internal surface of the shell 18, an inner cylindrical portion which is fluted to receive the splines 38 of the sleeve 11, and two axially spaced annular webs or flanges 46, 48 which extend radially between the cylindrical portions 40, 50. The splines 38 of the sleeve 11 hold the piston 39 against angular movement with reference to the shaft 10 but permit the piston to move axially between the caps 16. The end portions of the outer cylindrical portion 40 are provided with face cams 42, 44 whose lead is identical with that of the cams 34, 36. The piston 39 comprises two halves which abut against each other in the plane of the line II-II of FIG. 1 and are permanently or separably secured to each other.

The flanges 46, 48 are provided with pairs of openings or bores which are parallel to the axis of the shaft 10 and are located diametrically opposite each other. Each opening 60 of the flange 46 registers with an opening 60 of the flange 48. These openings accommodate the end portions of two guide pins 56 forming part of two automatic fluid flow regulating valves each mounted in one of two passages 52 of the piston 39. One of these regulating valves is shown in detail in FIG. 3. The median portion of each guide pin 56 is provided with a collar 54 which separates two helical valve springs 58. Each of these springs bears against one of the flanges 46, 48 and against the collar 54 so as to urge the guide pin 56 to a neutral position shown in the upper part of FIG. 1. Each collar 54 is integral with a crosshead or carrier 51 which is rigid or integral with two cylindrical valve members 62 located diametrically opposite each other with reference to the axis of the corresponding guide pin 56. The end portions of the valve members 62 are of conical shape and taper away from the central portions of such valve members. Each opening 60 of the flange 46 or 48 is flanked by two ports 66, 68 which form part of the respective passages 52 and register with the valve members 62. The inner annular edges of surfaces which surround the ports 66, 68 can serve as seats for the adjoining conical end portions 70 of the respective valve members 62.

The operation:

The end portions 12 of the shaft 10 are fixedly mounted in the frame of the roller conveyor so that the shaft is held against rotation. The braking roller of FIGS. 1 to 3 is installed between two idler rollers of the roller conveyor, between an idler roller and a second braking roller, or between two additional braking rollers. When an article is caused to travel along the roller conveyor, its bottom surface engages the external surface of the shell 18 and causes the latter to rotate about the shaft 10. In order to insure stronger frictional engagement between the shell 18 and the underside of the travelling article or articles, the external diameter of the shell 18 may exceed slightly the external diameters of adjoining idler rollers in the roller conveyor. Alternatively, or in addition to such dimensioning of the shell 18, the braking roller can be mounted on springs so that the shaft 10 can move up and down and is biased upwardly in order to maintain the top portion of the shell 18 in the path of movement of the underside of an article which travels along the roller conveyor. Still further, the external surface of the shell 18 may be roughened by grooving, milling or in another suitable way to insure more satisfactory frictional engagement with travelling articles. The shell preferably comprises an external liner or coating of rubber or other suitable elastomeric material.

The rotational speed of the shell 18 with reference to the shaft depends on the speed of the article which engages its external surface. In response to rotation of the shell 18 which is shared by the cams 34, 36 of the caps 16, one of these cams engages the adjoining cam 42 or 44 of the piston 39 and causes the latter to move axially along the sleeve 11 of the shaft 10. The other cam of the piston 39 then engages the adjoining cam of the revolving housing and causes the piston to move axially in the opposite direction. In other words, the cams 34, 36 of the caps 16 cooperate with the earns 42, 44 to move the piston 39 axially back and forth between the caps of the braking roller. In this way, the piston 39 increases the volume of the right-hand chamber 19b of the compartment 19 at the expense of the left-hand chamber 19a of this compartment, or vice versa, depending on the direction in which the piston moves in the shell 18. The compartment 19 is filled with oil or another suitable liquid and such liquid is caused to flow through the passages 52 in response to axial displacement of the piston 39.

The springs 58 of the two regulating valves normally maintain the conical end portions 70 of the valve members '62 away from engagement with the adjoining seats in the flanges 46, 48. Thus, when the shell 18 is set in rotary motion by an article which travels slowly along the roller conveyor, the piston 39 changes its axial position at a low speed so that the liquid can flow between the end portions 70 and the adjoining seats without effecting any appreciable axial displacement of valve members 62 with reference to the piston. In other Words, the braking roller then produces a minimal braking action or no braking action at all. However, when the shell 18 is engaged and rotated by a rapidly advancing article, the rate of fluid flow between the chambers 19a, 19b of the compartment 19 increases and the fluid exerts pressure against the end portion 70 at one end of each valve member 62 to change the axial positions of such valve members with the result that the trailing end portions 70 (as considered counter to the direction of fluid flow through the respective passages 52 of the piston 39) move against or close to their respective seats and thus throttle the flow of liquid through the piston. Consequently, the piston 39 Opposes rotation of the shell 18 and the latter produces a strong braking action. It will be readily understood that the magnitude of braking force produced by the shell 18 upon travelling articles is directly proportional with the speed and kinetic energy of articles which advance along the roller conveyor. Inversely, and as mentioned hereinabove, the braking action is less pronounced or practically nonexistent when the articles are caused to travel at a lesser speed. Furthermore, and if the article which rotates the shell 18 is rather long, the braking action of the shell upon such article decreases gradually as the article continues to move therealong. This will be readily understood since, when the article is decelerated in response to initial engagement with the shell 18, the valve members 62 offer lesser resistance to the flow of liquid through the respective passages 52 and the braking action of the shell 18 decreases. This is due to the provision of springs 58 which always tend to maintain the valve members 62 in neutral positions in which the end portions 70 of such valve members offer a minimal resistance to the flow of liquid through the respective passages 52.

The braking action of the improved roller depends negligibly on the weight and/or bulk of conveyed goods, i.e., such braking action is dependent mainly on the speed of goods, and the shell 18 is capable of satisfactorily 6 braking a large, small, short, long, heavy or lightweight article with equal efficiency.

The shaft 10 of the braking roller preferably consists of steel or other suitable metallic material. All or nearly all other component parts of the braking roller can be made of synthetic plastic material and can be massproduced in accordance with any of several well known manufacturing processes. The use of plastic materials brings about a reduction in the weight and cost of the braking roller. Moreover, the maintenance cost of the braking roller is negligible and its useful life is surprisingly long.

FIGS. 4 and 5 illustrate a modified braking roller. The median portion of the shaft is of polygonal (preferably hexagonal) cross-sectional outline and the shaft has two externally threaded end portions 82 by means of which it can be mounted in the frame of a roller conveyor in the same Way as described in connection with FIGS. 1 to 3. The polygonal median portion of the shaft 80 is provided with a plastic sleeve 102 which has six equidistant axially parallel ribs or splines best shown in FIG. 5 and extending into complementary flutes provided in the internal surface of a cylindrical portion 106 forming part of an axially reciprocable pumping member or piston 139'.

The plastic shell of the housing of the braking roller is integral with two end walls or caps 84 which can rotate on the outer races of two antifriction bearings 98 and have their central openings sealed by nuts 96 which mesh with the respective end portions 82 of the shaft 80. The shell 90 comprises two cupped sections 90a, 90b whose open ends abut against each other, as at 92. A coupling member 94 of hardenable plastic material surrounds the abutting ends of the sections 90a, 90b to provide a fluidtight seal and to hold the sections against axial and/or angular movement relative to each other. The coupling member 94 is formed subsequent to mounting of sections 90a, 90b on the shaft 80, Le, subsequent to insertion of the piston 139. Each cap 84 has, a cylindrical portion 86 which is adjacent to the respective axial end of the shell 90 and is formed with a helical face cam 88. The cams 88 are formed by the helical shoulders between the cylindrical portions 86 and the adjoining ends of the shell 90. The two earns 88 are angularly offset by 180 degrees with reference to each other. Sealing elements are installed in the caps 84 inwardly of the respective antifriction bearings 98.

In addition to the aforementioned inner cylindrical portion 106, the piston 139 comprises an outer cylindrical portion 104 which slides along the internal surface of the shell 90, and two flanges which extend radially be tween the cylinders 104, 106. The piston 139 has two face cams 108 each of which cooperates with one of the cams 88. The lead of cams 108 is the same as that of the cams 8-8.

Each flange 110 has a port 112 and the port of one of the flanges is located diametrically opposite the port of the other flange. The outer edge of the annular surface surrounding each port 112 constitutes a seat for a poppetlike valve member 116 forming part of one of two regulating valves which are installed in an internal chamber 111 of the piston 139. The chamber 111 and the two ports 112 constitute a passage through which the braking liquid can flow between the chambers 180a, 1801; of the compartment 180 defined by the housing 89, 90, 89 and the sleeve 102 of the shaft 80. The stems 114 of the valve members 116 are surrounded by prestressed helical valve springs 120 which are attached to disk-shaped retainers 118 at the inner ends of the respective stems 114 and to the adjoining flanges 110'. Each spring 114 tends to urge the respective valve member 116 away from the respective seat. In other words, when the piston 139 is at a standstill or when the piston moves slowly toward the one or the other of the caps 84, the chamber 111 is free to communicate with the chambers a, 1801) of the compartment 180 in the shell 90.

The operation of the just described braking roller is very similar to that of the braking roller shown in FIGS. 1 to 3. When the shell 90 rotates rapidly and the piston 139 travels in a direction to the right, as viewed in FIG. 4, liquid in the right-hand chamber 180b of the compartment 180 causes the lower valve member 116 to bear against the seat on the right-hand flange 110 and to thus oppose rotation of the shell 90 which latter thereby brakes the article travelling along the roller conveyor. When the piston 139 thereupon moves to the left, as viewed in FIG. 4, the upper valve member 116 is caused to move toward or to engage its seat and to thus again oppose rotation of the shell 90. The braking action is again proportional to rotational speed of the shell.

It is clear that the improved braking roller can be modified in a number of ways without departing from the spirit of my invention. For example, the braking roller can be equipped with other types of regulating valves, such as annular valves or the like. Furthermore, the braking roller of FIGS. 1 to 3 could be provided with a single regulating valve and the roller of FIGS. 4-5 can be provided with two or more pairs of regulating valves.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. A braking roller for use in roller conveyors or the like, comprising a shaft; means for holding said shaft against rotation; a hollow housing including a cylindrical shell and two end walls rotatably mounted on said shaft so that the housing can rotate in response to engagement between the external surface of said shell and an article which travels along the conveyor, said housing defining with said shaft a liquid-filled compartment; a piston axially movably mounted on said shaft and dividing said compartment into a pair of chambers; cooperating cams provided on said piston and said housing and arranged to move the piston back and forth in response to rotation of said housing, said piston having at least one passage extending between said chambers; and regulating valve means provided in said passage to throttle the flow of liquid between said chambers at a rate which increases in response to increasing rotational speed of said housing.

2. A braking roller as defined in claim 1, wherein said cams comprise a first pair of face cams each provided on one of said end walls and a second pair of face cams provided at the ends of said piston, one cam of said first pair cooperating with one cam of said second pair when the piston moves in one direction axially of said shaft and the other cam of said first pair cooperating with the other cam of said second pair when the piston moves in the opposite direction.

3. A braking roller as defined in claim 2, wherein said face cams are helical cams and wherein the lead of all of said cams is the same, one cam of said first pair being angularly offset by 180 degrees with reference to the other cam of said first pair.

4. A braking roller as defined in claim 1, wherein said regulating valve means comprises a valve member which is movable in said passage to and from a neutral position in which said valve member offers a minimal resistance to the flow of liquid between said chambers, and means for yieldably urging said valve member to neutral position.

5. A braking roller as defined in claim 1, wherein said passage has two axially spaced ends and said piston defines a pair of valve seats at the ends of said passage, said regulating valve means comprising a valve member disposed in said passage and having two end portions each movable against one of said seats, and resilient means for urging said valve member to a position substantially midway between said seats so that said valve member then offers a minimal resistance to the flow of liquid between said chambers, such resistance of said valve member increasing automatically in response to movement of said piston with reference to said shaft at a speed which is high enough to cause the liquid flowing through said passage to effect axial displacement of the valve member to move one of said end portions nearer to the respective seat.

6. A braking roller as defined in claim 5, wherein said end portions of the valve member are of conical shape and taper in directions away from each other.

7. A braking roller as defined in claim 5, wherein said piston is further provided with a second passage and said valve means comprises a second valve in said second passage, and guide means axially movably mounted in said piston and supportingly connected with said valve members, said resilient means operating between said guide means and said piston.

8. A braking roller as defined in claim 7, wherein said guide means comprises a collar substantially midway between its ends and wherein said resilient means comprises a pair of helical springs surrounding said guide means and each operating between said piston and one side of said collar to thereby urge said guide means to a neutral position corresponding to such positions of said valve members in which the valve members offer minimal resistance to the flow of liquid through the respective passages.

9. A braking roller as defined in claim 1, wherein said piston comprises two axially spaced flanges and said passage comprises a third chamber between said flanges and a port provided in each of said flanges, said regulating valve means comprising a pair of valve members each adjacent to one of said ports and resilient means for urging said valve members away from said ports to thus permit substantially unobstructed flow of liquid between the chambers of said compartment by way of said ports and said third chamber when the piston moves at a relatively low speed axially of said shaft, one of said valve members being moved toward the respective port to thus throttle the flow of liquid through such port when the piston moves at a speed which suffices to effect axial displacement of said one valve member in response to increasing liquid pressure in that chamber of said compartment whose volume is reduced in response to axial movement of the piston.

10. A braking roller as defined in claim 9, wherein said valve members are poppets.

11. A braking roller as defined in claim 9, wherein said valve members are of annular shape.

12. A braking roller as defined in claim 1, wherein said piston comprises an outer cylindrical portion in sliding engagement with the internal surface of said shell, an inner cylindrical portion surrounding said shaft, and at least one flange integral with and extending between said cylindrical portions.

13. A braking roller as defined in claim 1, wherein said shaft consists of metallic material and further comprising a plastic sleeve surrounding said shaft and slidably supporting said piston.

14. A braking roller as defined in claim 1, further comprising spline means and complementary flute means extending in the axial direction of said shaft and arranged to hold said piston against rotation on said shaft, one of said last mentioned means being provided on said shaft and the other of said last mentioned means being provided on said piston.

15. A braking roller as defined in claim 14, wherein said shaft is provided with a plastic sleeve and wherein said spline means is provided on said sleeve.

16. A braking cylinder as defined in claim 1, wherein said cams comprise a pair of face cams provided on said end walls.

9 10 17. A braking roller as defined in claim 1, wherein References Cited Said end Walls are integral said Shell. P

18. A braking roller as defined in claim 1, wherein I said shell comprises two cylindrical sections arranged 3:399752 9/1968 Orwmend-to-end and further comprising coupling means sealingly securing said sections to each other. 5 FOREIGN PATENTS 19. A braking roller as defined in claim 1, wherein the 200,412 12/ 1965 Sweden. external surface of said shell is roughened. 1,189,917 3/1965 Germany.

20. A braking roller as defined in claim 1, wherein said 1,289,779 2/1969 Germany. shell is provided with an external liner of elastomeric material, 10 ANDRES H. NIELSEN, Primary Examiner 21. A braking roller as defined in claim 1, wherein said housing and said piston consist of synthetic plastic material. 74230.01 

